A high-pressure pump such as described in our copending and commonly assigned application Ser. No. 954,549 has a pumping chamber whose volume is periodically increased and decreased, normally by reciprocation of a piston. A so-called valve head or unit is attached to the housing of this pump and itself has a valve chamber communicating with the pumping chamber of the pump. This valve unit or assembly is formed with an intake port and at least one exhaust port, and is provided with check valves at each of these ports for one-way flow through the valve chamber.
In a common valve assembly used in a high-pressure piston pump the intake and exhaust ports are axially aligned with each other and open axially oppositely into the valve chamber. Each of these ports is associated with a respective valve body urged into sealing engagement over the respective port by a respective spring. Each of these valve bodies is a simple imperforate disk and is guided in a respective cage that also houses the respective spring. These two guides can be constituted as tubes which are received in the pumping chamber and which bear axially oppositely against each other. These guide tubes are in turn formed with relatively large openings serving for traversal by the pumped fluid, and also with several smaller holes whose function mainly is to allow fluid to enter the tubes and act on the respective valve bodies.
The above-described system is relatively complex, and is highly prone to wear. Furthermore the operation of such valves is typically relatively sluggish, so that during the response time backflow is possible, with corresponding loss of pressure and pump efficiency.